Froth flotation of phosphate ore



Patented Mar. 4, 1947 safes mcs FROTH FLO'I'ATION F PHOSPHATE ORE NoDrawing. Application May 13, 1942, Serial No. 442,818

4 Claims. (Cl. 209-166) This invention relates to an improved method forthe froth flotation of phosphate ores using the so-called anionicflotation agents.

The problem of beneflciating phosphate rock by froth flotation methodsis considerably complicated by the fact that the phosphate is arelatively low priced material and that the flotation operation resultsin floating a relatively large weight of material in the form of aconcentrate. There is no problem at all in floating most phosphate rockqualitatively. Any of the common flotation agents for non-metallicmaterials such as fatty acids and fatty acid soaps will float phosphate,but in order to achieve a commercial resuit it is necessary to obtain ahigh grade of con centrate as a relatively large premium is paid forgrade. obtained with a reasonable reagent cost and with a fair degree ofrecovery.

It was found that when soaps were used to float phosphate rock, resultswere not satisfactory. The next development was to use fatty acids,caustic alkali and hydrocarbon or other nonsaponiflable diluents. Thisprocedure resulted in a commercial process which is used almostexclusively in the Florida Pebble Phosphate field. Further improvementsresulted when fatty acids were substituted by talloel which is a mixtureof unsaturated aliphatic acids and rosin acids, and.

this combination of reagents represents the best commercial efliciencyachieved with the caustic alkali hydrocarbon oils and acid process.

The present invention is a departure from the procedure which wasfinally worked out after years of investigation and goes back in part tothe use of a type of reagent which was considered unsatisfactory forphosphate flotation, namely the use of soaps instead of the free acidsadmixed with caustic alkali so as to form compounds in situ. It wasfound that if instead of using a non-saponiflable diluent such as fueloil, a saponifiable oil At the same time, this result must be.

the same amount are therefore misleading because if as little soap isused as is equivalent to the fatty acid in the fuel oil process, therecoveries will be unsatisfactory, whereas if as much fatty acid is usedwith fuel oil as soap with saponifiable oil, the gradeis uncommercial.Therefore in comparative tests which will be shown in some of thespecific examples to follow, each type of reagent has been used in itsoptimum amount in order to obtain the best possible results with eachreagent. 1

Not only is there a difference between the amount of soap and the amountof free fatty acid to be used to obtain best results,'but results willvary somewhat with different soaps and of course in every case the bestproportions will be used.

It might be expectedthat a saponifiable oil in r the form of an esterwill behave differently than a s'aponiflable oil in the form of a freefatty acid. It would normally be expected that in the latter A case thefree fatty acid would act as a promoter,

which role it plays in processes using fuel oil as sociated with fattyacid. This, however, ap-

, pears not to be the case because talloel which is a mixture of fattyacids and rosin acids may be this surprising behavior has not beendetermined which is the ester of a polyhydric alcohol and exactly but itseems probable that promoter action may be tied up in some way with theamount of alkali present and that only the soap acts as a promoter, theunsaponified fatty acid behaving in a different manner, whereas whenlarger amounts of free fatty acids are used with fuel oil, largeramounts of soap are formed because the alkali is also present in such aprocess in large excess over the molecular equivalent to the fatty acidused.

A further practical advantage of the process of the present invention isthat it is relatively insensitive to changes in amount of collectorwithin fairly wide limits. While there is, of cours'e, an optimum amountof collector for each particular ore and for each particular collector,nevertheless the amounts may be .varied throughout a considerable range,which range is much broader than in the case of the known caustic soda,fatty acid, fuel oil process. This insensitiveness to changes in amountsof reagents is of considerable value in practical phosphate flotation asit removes a critical factor. Phosphate feed and EXAMPLE 1 A typicalphosphate feed from the Florida P'ebble Phosphate district havingbetween and 36% fuel oil and 0342 pound per ton of talloel. The reagentswere added in the order given while the mixer was continuouslyoperating. The pulp was diluted to flotation consistency and subjectedto froth otation in a Fagergren flotation machine as described inExample 1.

A further portion of feed was conditioned in the same manner but using0.25 pound per ton caustic. soda, 0.63 pound per ton of talloel and 4.00pounds per ton of #2 fuel oil. Conditionlng. dilution and flotation werethe same as above. tThai metallurgical results appear in the followingab e:

Table II Assays 1. Per cent distribution Lbs/ton feed Per cent Insol.B.P.L. Insol. B.P.L. NaQH Fuel oil Talloel Cleaned concentrate 40. 68 6.75 74. 67 4. 97 86. 80 0. 318 1. 794 0. 342 iddlin 8. 96 73. 64 21. 82ll. 92 3. 40 318 l. 794 342 50. 36 01. 40 6.82 83. 11 9.80 318 1. 794342 cc 100. 00 55. 38 35. 00 100. 00 100. 00 Cleaned concentrate.--" 44.28 9. 73 71. 82 7. 90 88. 75 250 4 000 630 lvliddling .1 10. 22 82. 9813. 22 15. 57 3. 77 250 4. 000 630 Rougher tailing 45. 91.62 5. 89 76.53 7. 48 250 4. 000 630 Feed 100. 00 54. 48 35. 83 100. 00 100. 00

B.P.L. was conditioned at 70% solids with 0.88 pound per ton ofsaponified talloel (sodium salts) and one pound per ton of coconut oil.The pulp was then diluted to 22% solids and subjected to froth flotationin a Fagergren flotation machine, the rougher concentrate beingcollected after short further conditioning.

The same feed was conditioned with 0.88 pound per ton of saponifiabletalloel and two pounds per ton of coconut oil and subjected to the sameflotation procedure. The metallurgical results are.

' shown in the following table:

It will be apparent that the addition of further amounts of fuel oilwhile it did somewhat raise the recovery, did have disastrous effects onthe grade, the amount of insoluble material becoming so high as to becommercially useless.

EXAMPLE 3 A high grade Florida pebble phosphate feed having from 43 to45% of B.P.L. was conditioned with a mixture of the sodium soap oftalloel and unsaponified talloel under the conditions described inExample 1, and was subjected It will be apparentv that the-gradeobtained is relatively insensitive to large increases in the amount ofcoconut oil used and high recovery is obtained thereby with only a smallsacrifice in grade.

to flotation as there described. The feed was sized -,20 mesh Variousproportions of talloel soap and talloel were used and the results forthe different proportions appear in the following table of metallurgicalresults-:53

Table III Feed Concentrates Middlings Tailin'gs ggg Ratio Recov.

B.P.L. Gms. B.P.L. 111501. Gms. B.P.L. Gms. B.P.L. Gms. 223 T311551 43.81 511 79. 03 3. 71 239 68. O2 31 5. 77 241 2. 14 84. 3 O. 44 1. 68 43.84 510 77. 49 5. 42 264 37. 29 29 3. 78 217 1. 93 91. 6 88 1.12 43. 08518 77. 45 4. 41 259 62. 23 19 4. 46 240 2. 0O 89. 9 32 1. 51 44. 32 51578. 20 3. (i6 245 68. 78 27 7. 45 243 2. 10 84. O 22 1. 61 44192 514 80.09 3. 79 234 72. 63 7. 36 245 2. 20 81. 0 1. 51

EXAMPLE 2 EXAMPLE 4 Feed of the type described in Example 3 wasconditioned with various amounts of sodium soap of talloei and coconutoil and floated as described 7 6 in the above example. The followingtable shows tslloel soap .per ton of feed and 1.18 pounds ofthemetaiiurgicai results: talloel per ton of feed and floated asdescribed Table IV r0011 00110011110100 Middlina Telling gg Ratio Recovv 3.2.1.. 0111:. B.P.L. 10001. 01111. 3.121.. Gms. 3.121.. Gms. v 22?4378 525 80.83 3.46 172 72.87 40 18.12 N4 3.05 60.5 0.64 1.28 44:29 614Bil-N 8 (D 218 07 74 33' 11.50 263 2.36 76.7 .76 1.53 14 613 76.03 3.73243 68.13 11.66 247 2.12 81.5 .88 1.75

1111111111.: a a 111 librample 4 with only a single cleaning 01 the Iconcentrate. Various amounts of slime were Alow grade Florida phosphatefeed containing deliberately added to the feed and it will be about 81%B.P.L. was conditioned with various 20 noted that the slimeproduces noadverse eiiect. amounts of talloel soap and talloel and floated as Theresults appear in the following table:

Table V1 11033 0011001100201 1111001111111 Talilngs Lb m Ratio Reeov 5131.1,. 01111 13.11.. 10.401. Gms B.P.L. Gms. B.P.L. Gms. ee eddescribed in Example 4 except that the concen- Exams: 7 trate wascleaned twice. The feed was 48 mesh.

The metallurgical results appear in the follow- An extremely low gradeFlorida pho p e d mg t ble; 40 containing about BBL. was conditioned andTable V Feed 00110011212100 Middlinp T1100 3 Rmmggbt/m 7 1 Ratio Recov.

11.1 .14" (31112 a 2.1. 111101 01115. 3.2.1.. Gm: 3.2.1.. Gms 3:?Tailoel 31. 02 403 73 a0 a 33 177 32 20 41 1. 11 277 2 3a 4 0. 40 1.1430.94 503 76. 71 6.30 186 33. 32 28 1.) 289 2.70 90.6 .33 1.25 31.33 0007021 000 132 3040 21 2.33 201 2.70 32.2 .22 1.38, 31.02 402 71130 300173 38.06 30 2.30 291 200 37.2 .11 1. 01 31.13 000 73.00 1120 202 17.3028 1.72 273 200 V 233 .22 1.00 31.22 002 7221 41s 10s 32.33 20 2.30 2302.07 10.7 .22 .74

Exam! 6 floated with varying amounts of talloel soap and coconut oil.The feed was -48 mesh and the A low grade feed as described in theforegoing m concentrate was cleaned twice. The results apexample wasconditioned with 0.22 pound oi. pearinthe following table:

Table VI! Feed Concentrates Middlings Tallinn 7 Reagents, lb.lton ieedRatio Reoov.

3.2.1.. 01115. B.P.L. 111101. one 3.2.1.. 01111.. 11.11.. 01111.. m?Talloel 3F 20 41 504 74.14 7.75 121 20.10 72 1.92 351 4.17 37.1 0.221.20 19 71 300 74 44 0.00 103 41.03 as 2.25 334 4.86 77.0 22 1.1a 10 so600 78.27 2.95 87 07.72 29 s.04 884 6.75 70.5 .34 1.29

EXAMPLE 8 2. A method of beneficiating phosphate ore by I frothflotation which comprises conditioning the A Florida pebble phosphatefeed from a differphosphate ore with from about 0.1 to about 1.3 entdeposit from that used in the foregoing eX- lbs. per ton of atalloelsoap and an amount of ample was conditioned with an ordinarysoap, coconut oil at least substantially equal in weight sodium silicate.and coconut oil in varying to the soap, and subjecting the conditionedore amounts, and single cleaning of the rougher conto froth flotation,removing a froth concentrate centrate was employed. The conditioningprorich in phosphate and a tailing poor in phosphate. cedure was thesame as in-the foregoing examples A method of beneficiating phosphateore by and the flotation time was also the same. The froth flotationwhich comprises conditioning the results appear in the following table:phosphate ore with from about 0.1 to about 1.3 Table VIII FeedConcentrates Middlings Tailings 'Midds. loss Middsroc. Lbs/ton icedggiig g V Vege- Sodi- Coco Vege- Sodi- 00cm B.P.L. Gms. B.P.L. IHSOI.Gms. B.P.L. Gms. B.P.L. Gms. Ratio Rec. Ratio R00. im 5% nut w gff nutsoap cute soap cate on .7 6.20 201 26. so 27 6. as 264 2.60 84.2 2. 4689.7 1. 29 0.26 1.22 3.34 2. 23 3.16 I

EXAMPLE 9 lbs. per ton of a talloel soap and an amount of l palm oil atleast substantially equal in weight to Phosphate feed from the samedeposit as Exthe soap, and subjecting the conditioned ore to ample 8 wasconditioned and floated using a fish froth flotation, removin a frothconcentrate rich acid soap, sodium silicate and coconut oil. 00m inphosphate and a tailing poor in phosphate. ditioning and flotationconditions were thev same 4. A method of beneficiatin phosphate ore byas in Example 8 and the metallurgical results froth flotation whichcomprises conditioning the appear inthe following table: p sphate orewith from about 0.1 to about 1.3

Table IX Feed Concentrates Middlings Tallings Midds. loss Midds. rec.Lbs/ton feed Lbs/ton c0110.

. Sodi- Sodi- I Coco- Coco- B.P.L. Gms. B.P.L. Insol. Gms. B.P.L. Gms.B.P.L. Grns. Ratio Rec. Ratio Rec. 5253 rgiilt gs; lzlfit cate cate34.04 620 76.01 4.25 176 54.41 34 7.93 310 2.95 75.6 2.61 {86.0 1.29!0.861112 3.112 2.55 3.63

EXAMPLE 10 lbs. per ton of a talloel soap and an amount of talloil atleast substantially equal in weight to the A further portion of thephosphate feed of soap, and subjecting the conditioned ore to frothExamples 8 and 9 was conditioned with talloel flotation, removing afroth concentrate rich in soap and palm oil, conditioning and flotationprophosphate and a tailing poor in phosphate. cedures being the same asin the two foregoing ex- 7 BRUCE DONALDSON CRAWFORD. amples.Metallurgical results are as follows: DAVID WALKER JAYNE, JR y 1 Table XFeed Concentrates I Middlings Tailin gs Midds. loss Midds. rec. Lbs/tonfeed I Lbs/ton cone. B.P.L. Gms. B.P.L. Insol. Gms. B.P.L. Gms. B;P.L.(lms. Ratio Rec. Ratio Rec. gg g g f z g g 34.36 516 73.94! 7.70 211'27.31! 28 4.92 277 245,630! 2.341923 I 1.22 1.80! 2.97! 4.40 The resultsobtained in'EXamples 8 to 10 are REFERENCES CITED not comparable withresults of Examples 1 to 7 A 4 because the phosphate feed was from adifferent The followmg references are of r d in the deposit. In generalthe feed used in Examples file of t P 7 1 1 to '7 is somewhat better inits behavior in tation under the process of the present invention.UNITED STATES PATENTS We claim: I Number Name 1 Date 1. A method ofbeneficiating phosphate ore by 1,547,732 adb ge et a1. July 28, 1925froth flotation which comprises conditionin the 6 OgeLJorgensen July 11,1939 phosphate ore with from about 0.1 to about 1.3 P ,986,8 6Hasselstrom Jan.'8, 1935 lbs. per ton of a talloel soap and an amount of2,014,406 Weed Sept. 17, 1935 saponifiable oil at least substantiallyequal in 2,156,245 Mead et al. Apr. 25, 1939 Weight to the soap, andsubjecting the conditioned ore to froth flotation, removing a frothconcentrate rich in phosphate'and a tailing poor inphosp hate. 75

